SAN FRANCISCO (CBS SF) – As more and more smartphones offer fingerprint scanners to unlock the device or approve payments, a new study should give device owners pause.

While other methods of fooling fingerprint scanners have been documented before, Michigan State University researchers Kai Cao and Anil Jain were able to spoof the fingerprint scanners on Samsung Galaxy S6 and Huawei Honor 7 phones with the use of an inkjet printer.

In their experiment (.pdf), Cao and Jain printed out fingerprints they scanned with special conductive ink and glossy paper.

The team found spoof fingerprints could unlock both phones, with the Huawei being slightly more difficult to hack.

“This experiment further confirms the urgent need for antispoofing techniques for fingerprint recognition systems, especially for mobile devices which are being increasingly used for unlocking the phone and for payment,” the authors wrote.

The researchers also raised worries that hackers could eventually spoof other biometric security methods, saying “it is only a matter of time before hackers develop improved hacking strategies not just for fingerprints, but other biometric traits as well that are being adopted for mobile phones (e.g., face, iris and voice).”